As a consequence of the hydraulic adjustment, the toothed engagements are completely eliminated, which, however, is already the case today in existing hydraulic systems. The disadvantage resides in the central hydraulic system in the machine housing of the wind energy system and of the supply line into the rotor resulting from it. The interface between the machine housing and the rotor must be constructed with expensive rotary transmission leadthroughs. Therefore, the hydraulic supply must be must be run through the entire main transmission, which makes correspondingly expensive hollow shafts absolutely necessary.
In the known electrical systems blade supports with outer cogging or inner cogging are used in combination with a pivot drive. There are solutions in which the cogging is replaced by belt drives. The torque produced by an electromotor is transmitted via a planet transmission with a drive pinion onto the cogging of the blade support of the rotor blade, as a result of which a pivot movement of the rotor blade is induced. The electromotor is electrically connected into the rotor. The electrical energy is then transmitted via slip ring bodies from the machine housing into the rotor.
However, in electrical systems based on an adjustment via rotary drives the problem regarding the formation of wear on the cogging constantly reoccurs on account of the fact that an only small adjustment angle pitch is present in particular in the so-called 0° position, that is, the adjustment position between the cut-in wind speed and the nominal wind speed.
A wind energy system is already known from WO 2009/064264 that comprises a pitch adjustment system with an electrohydraulic drive, wherein the components of the electrohydraulic drive are arranged in the rotor of the wind energy system. The arrangement of the electrohydraulic drive in the hub or the rotor can eliminate a hydraulic leadthrough through the rotary connection between the hub and the rotor and the pod. The electrical motor in this known electrohydraulic arrangement is regulated or controlled in such a manner that the volume current of the hydraulic fluid can be adjusted as a function of the motor regulation or motor control. Furthermore, this previously known wind energy system already comprises a hydraulic reservoir via which the rotor blade is brought into a secure position in case of a system error.
The current electromechanical adjustment systems according to the prior art and the previously cited electrohydraulic actuators require an expensive electronic performance system. In the available systems no compact solution has yet been realized that comprises all necessary functions such as regulating operation, emergency pitching out in case of a current outage and a mechanical locking in a secure position.
The present invention therefore has the problem of further developing a wind energy system of the initially cited type in an advantageous manner, in particular in such a manner that a wind energy system is equipped with a compact and functionally reliable pitch system without an expensive electronic performance system.
This problem is solved in accordance with the invention by a wind energy system with the features of claim 1, that provides that a wind energy system is made available with at least one pitch adjustment system for adjusting the pitch of at least one rotor blade of the wind energy system, wherein the pitch adjustment system comprises at least one electrohydraulic drive with at least one hydraulic cylinder, at least one hydraulic reservoir, at least one adjustment valve, at least one electromotor pump unit and at least one control unit in which at least the hydraulic components including the at least one hydraulic cylinder and the at least one hydraulic reservoir are combined in a device and are arranged in it or on the rotor of the wind energy system, wherein the electrohydraulic drive comprises at least one electromotor rotating in one direction of rotation in an unregulated manner for generating pressure.
The unregulated electromotor with only one direction of rotation can advantageously drive one or more pumps. The using of several pumps makes possible an actuator adjustment with different adjustment speeds, as a consequence of which the motor drive moment can be reduced at high loads.
Preferred embodiments of the invention result from the subclaims following the main claim.
According to the above, the hydraulic cylinder of the electrohydraulic drive can comprise a lock in such a manner that at least one locking bolt engages into at least one recess in the piston rod. As a result of this locking in the piston rod, the external locks that are otherwise customary can be eliminated. The at least one locking bolt can be advantageously provided with a position recognition system for detecting its position.
According to another advantageous embodiment of the invention the mechanism for loosening the locking can be directly coupled to the pressure of a hydraulic reservoir in such a manner that the loosening of the lock only takes place when the hydraulic reservoir is charged to a given pressure. As a result an additional valve can also be eliminated.
In order to be able to regulate different adjustment speeds at least two pumps driven by a motor can be provided that can be cut in and out via switchable bypass valves.
The at least one other pump can only be cut in if the external load present is below a given threshold value.
It is quite especially preferred in the operation of the adjustment cylinder if a cylinder chamber is connected to the pump while the other cylinder chamber is connected to a reservoir.
A special advantage results in the present invention if at least one reservoir is charged to a pressure that is elevated in comparison to the pressure level of the hydraulic system for moving the at least one blade into a secure position. This creates a fail-safe system so that even in the case of a stoppage of the control- and energy supply unit present in the machine room the pitch system can be activated in order to rotate the rotor blades out of the wind.
An especially compact structure of the electrohydraulic actuator results if all hydraulic components are arranged on the central valve plate or are at least connected to each other by the latter.
The electromotor as well as the hydraulic pump can advantageously be built into the pre-tensioned tank of the hydraulic reservoir. As a consequence, the engine can be liquid-cooled and on the whole built to be smaller.
According to another embodiment of the invention an additional support bearing with low rigidity is constructed on the bottom of the electrohydraulic actuator in such a manner that the axial forces of the hydraulic cylinder of the actuator are introduced via the main support into the hub structure, wherein the additional support bearing receives only the components of the forces of weight and/or of mass that bring about a torque about the axis of the hydraulic cylinder.
The wind energy system can comprise at least two rotor blades, that are arranged on the rotor. A hydraulic adjustment unit can be associated with each rotor blade.
The invention furthermore relates to a pitch adjustment system for a wind energy system with the features of the pitch adjustment system in accordance with one of the previous claims.
Further details and advantages of the invention will now be explained in detail using an exemplary embodiment shown in the drawings.